Endless chain type cutter

Abstract: An endless chain (1) provided with groups of cutter elements (A-J) thereon, for cutting a ditch in the ground, the cutter elements (A-J) of each group, together being arranged to cut the ground throughout the width of the ditch. In excavating a ditch the cutter is advanced horizontally at a rate such that in the time the chain has moved a distance corresponding to the length of one group of cutter elements, the cutter has moved horizontally by less than the distance by which the cutter bits project from a base plate of the cutter element.

Description: The present invention relates to an endless chain type cutter for excavating a ditch in the ground for use when constructing an underground continuous wall in civil engineering works. Previously, in order to construct an underground continuous wall, it was necessary to excavate an elliptical hole, 2 or 3m (6 or 10 feet) wide, down to a predetermined depth from the ground surface, or to drill into the ground with an auger drill with double or triple lanes down to a predetermined depth, and then to insert a reinforcement cage or steel members. Finally, cement was poured into the hole, or ready mixed concrete was cast in the hole. By repeating this process with successive holes intercepting preceding ones, a continuous underground wall could be constructed. In the prior method for constructing an underground continuous wall described above, there are some problems as follows. Since the machinery for excavating the holes is about 30m (100 feet) tall, there is a danger that it may fall over. Secondly, the construction process is complicated, so the construction period is prolonged. Also, a film of muddy water, bentonite or the like is formed where one hole intercepts the preceding section of wall, so a perfect joint cannot be made in order to form a continuous wall. Underground water may leak through the joints after completion of the works. It is therefore difficult to attain simultaneously the objectives of safely and rapidly constructing a wall in the ground which is also perfectly continuous. Because of these problems, a method of making an underground continuous wall as shown in the schematic views of Figs. 8 and 9 has been tried. In this method an endless chain type cutter c is disposed on one side of a self-propelled vehicle b having crawler tracks a. A continuous ditch is excavated in the ground by advancing the self-propelled vehicle b in the direction of the arrow A of Figs.8 and 9 while driving the cutter c. Then cement or concrete is poured into the ditch. In the endless chain cutter c mentioned above, an endless chain f is spanned between upper and lower chain sprockets d and e and groups of cutter elements are disposed protrudingly on the outer side of this chain f at predetermined intervals. Within each group of cutter elements, cutter bits g 1 - g 9 are arranged on base plates h, attached to the chain f, for example as shown in Fig. 10. When the chain cutter having cutter bits g 1 - g 9 as shown in Fig. 10 is advanced in the direction of the arrow A in Figs. 8, 9 the sprockets d and e are rotated to drive the chain so that the cutter bits move in the upward or downward directions of the drawings. The excavating loci i 1 - i 9 as shown by hatched lines in Fig.10 are made on the ground in the upright face which is being cut in front of the cutter c. If the ground to be excavated is weak, then it can be efficiently excavated by the above-mentioned excavating loci i 1 - i 9 . However, in the case where the ground is hard and strong, there is a problem that the portions j 1 - j 7 (see Figure 10) of the ground in front of the cutter remain in place. When these remaining portions hit the outer surface of the base plate h or the endless chain f, these meet with increased resistance, so that the continuation of the excavating work is hampered. The present invention aims to overcome this and other problems. AU-A-540966 and EP-A-0 522 765 both disclose endless chain cutters for excavating a ditch in the ground, and having projecting cutter bits. In the present invention there is provided an endless chain type cutter having an endless chain (1) extending between upper and lower sprockets (d, e) and at least one group of cutter elements (A-J) thereon for use in cutting, in the ground, a ditch of pre-determined width (K), each cutter element (A-J) having at least one projecting cutter bit (4), characterised by the cutter bits (4) of the cutter elements (A-J) of each group, together, being arranged to cut the ground continuously across the entire width (K) between the laterally outermost cutter bits (4) of the group of cutter elements, so that no part of the ground across the width of the ditch remains uncut by a cutter bit. With the invention, therefore, each group of cutter elements can cut each part of the ground in the width of the ditch being cut, ensuring that the ground is disturbed and loosened throughout the width of the ditch. Typically, there are about ten elements in a group, and some elements are preferably of bucket type. The number of groups on the chain will depend on its length, but 4 to 8 groups may be typical. The invention also provides apparatus for excavating a ditch including a vehicle, which is preferably a tracked vehicle, with such an endless chain type cutter mounted thereon. The invention also provides a method of excavating a ditch using such an endless chain type cutter in which, in a time in which the endless chain moves along its path between the upper and lower sprockets by a distance corresponding to the length of a said group of cutter elements, the endless chain is advanced along the direction of the ditch being cut by a distance which is less than the distance by which the cutter elements project from the chain. This method ensures that, even if the ground is hard and strong the chain itself will not engage the ground being cut. The invention will be further understood from the following description, when taken together with the attached drawings, which are given by way of example only, and in which: Fig.1 is a side view showing part of an endless chain type cutter according to the present invention with a group of cutter elements thereon; Fig.2 shows at (a) a front view of one example of a cutter element, and at (b) and (c) plan and side views of that element; Fig.3 shows at (a) a front view of another cutter element, and at (b) and (c) plan and side views of that element; Fig.4 is an explanatory view showing schematic plan views of the cutter elements of a group of cutter elements A-J, arranged in the order in which they are attached to the chain; Fig.5 is an explanatory view showing the excavating loci and progress along the cutter face of the various kinds of cutter elements of the group A-J, shown in Fig.4; Fig.6 is a sectional elevational view showing the cutting performed by corresponding cutter bits in adjacent groups; Fig.7 is a schematic side view of a cutter element; Fig.8 is a schematic elevational view showing one example of an excavating apparatus for cutting ditches used in constructing underground continuous walls; Fig.9 is a schematic plan view of the apparatus of Fig.8; and Fig.10 is an explanatory view showing an arrangement of a prior endless chain type cutter and excavating loci thereof. An embodiment of the present invention is described hereinafter with reference to Figs.1 to 7. Fig.1 is a side view showing part of an endless chain of an endless chain type cutter according to the present invention, in which reference numeral 1 denotes the endless chain. In the present embodiment, there are provided groups of different kinds (in this embodiment, 10 kinds A-J) of cutter elements attached to an endless chain 1. In this embodiment there are ten elements, A-J, in the group. These cutter elements A-J are arranged on the outside of the endless chain 1 at appropriate intervals. Fig.2 shows the cutter element A; in the drawing, 2 is a base plate, 3 is a cutter bit holding member disposed protrudingly on the base plate 2 at a predetermined position and a predetermined angle, and 4 are cutter bits disposed protrudingly on these cutter bit holding members 3. In Fig.4, element A is shown in a schematic plan view. The other cutter elements B, C, D, F, G, H and I are also shown schematically in Figure 4. Although the position and the angle of each of the cutter bits 4 are different from the cutter element A, they have essentially, the same construction as the cutter element A. Fig.3 shows a cutter element E. This comprises a bucket-type main body 5 attached to the outer side of the chain 1, and two cutter bits 4 disposed protrudingly on the outer side edge of the main body 5. At 5a are a plurality of holes made on a curved bottom wall of the main body 5. The cutter element J, also schematically shown, as is element E, in Figure 4, has essentially the same construction as cutter element E, but the positions of the cutter bits 4 are different from those in the cutter element E. Groups of cutter elements A-J are arranged continuously on the endless chain. The cutter bits 4 of each group of cutter elements A-J are arranged such that their respective excavating loci, which are shown by the correspondingly marked hatched lines in Fig.5, cover the entire width K of the ditch. In using the endless chain type cutter to excavate a ditch, the chain is driven between the upper and lower sprockets such that in a certain time it moves a distance L (refer to Fig.5) corresponding to the length of a group of cutter elements A-J. In the method of the invention, in the same period of time, the chain cutter is advanced gradually horizontally through a distance M (refer to Fig.6) into the ground being excavated. The distance M is made smaller than the distance N (refer to Fig.7) by which the cutter bits 4 project from the base plate 2 of cutter elements A, B, C, D and F, G, H, I. The distance M is also smaller than the length O (refer to Fig. 3(c)) by which the bucket-type cutter elements E and J project forward from the chain 1. As a result, even if the ground to be excavated is hard and strong, since the cutter bits 4 of a group of cutter elements cut the ground over the entire width of the excavated ditch, and since the horizontal distance advanced by the cutter when the same kind of cutter element comes up to the same vertical position in the ditch is smaller than the length N by which the cutter bits 4 protrude from the base plate 2, the outer surface of the base plate 2 and the chain 1 do not come into contact with the ground being excavated. The ground is loosened by all the elements A-J, while bucket-type elements E and J also collect and elevate to the surface, in order to be disposed of, ground which has been loosened. In a typical example, the width K of the excavated ditch is 550mm (about 1.8 feet), the length L of one group of cutter elements A-J attached to the chain is 4064mm (about 13.3 feet), the horizontal distance M advanced by the cutter, when the cutter chain moves a distance L, is 11mm (0.43 inches) and the maximum protruding length N of each cutter bits 4 on the base plates 2 of each cutter element A, B, C, D, F, G, H and I is 136mm (5.4 inches).

Claims: An endless chain type cutter having an endless chain (1) extending between upper and lower sprockets (d, e) and at least one group of cutter elements (A-J) thereon for use in cutting, in the ground, a ditch of pre-determined width (K), each cutter element (A-J) having at least one projecting cutter bit (4), characterised by the cutter bits (4) of the cutter elements (A-J) of each group, together, being arranged to cut the ground continuously across the entire width (K) between the laterally outermost cutter bits (4) of the group of cutter elements, so that no part of the ground across the width of the ditch remains uncut by a cutter bit. An endless chain type cutter according to claim 1, wherein at least one cutter element (E,J) of each group includes a bucket. An endless chain type cutter according to claim 2, wherein the or each bucket (5) has at least one cutter bit (4) projecting therefrom. An endless chain type cutter according to any one of the preceding claims wherein each group includes cutter elements (A-D,F-I) which have a plurality of cutter bits (4) projecting from a base plate (2) which is attached to the chain (1). An endless chain type cutter according to claim 4, wherein at least some cutter elements (A-D,F-I) include cutter bits (4) which project from the base plate (2) outwards beyond the edge of the base plate. Apparatus for excavating a ditch including a vehicle (b), such as a tracked vehicle with an endless chain type cutter according to any of the preceding claims mounted thereon. A method of excavating a ditch using an endless chain type cutter according to any one of claim 1 to 5 or apparatus according to claim 6 wherein, in a time in which the endless chain (1) moves along its path between the upper and lower sprockets (d,e) by a distance corresponding to the length (L) of a said group of cutter elements (A-J), the endless chain is advanced along the ditch being cut by a distance (M) which is less than the distance (N,O) by which the cutter elements project from the chain. A method of constructing a continuous underground wall by excavating a ditch according to the method of claim 7, and pouring cement or concrete therein.

Inventors: KITANAKA KATSUMI, KITANAKA, KATSUMI
Applicants: KOBE STEEL LTD, TOMEN KENKI CORP, KOBE STEEL, LTD, TOMEN KENKI CORPORATION
Application year: 1994
Main classification: E02F3
IPC codes: E02F3, E02F5, E02D17